The authors report an efficient way of incorporating single-wall carbon nanotubes (SWNTs) into alumina matrix with strong interfaces by heterocoagulation. The fracture toughness of SWNTs/Al2O3 composite reaches 6.40 +/- 0.3 MPa m(1/2), which is twice as high as that of unreinforced alumina. The flexure strength of the composite also increases by 20%. The main toughening mechanism is crack bridging of SWNTs, and SWNT pullout takes effect also. (c) 2006 American Institute of Physics.